Many medical procedures require the use of a cannula, through which one or more medical instruments are inserted into a patient and then removed from the patient. For example, in a variety of laparoscopic medical procedures, a cannula is positioned with its distal end inside the patient and its proximal end outside the patient. One or more medical instruments can be inserted through the cannula into the patient. For example, each of a sequence of instruments (including an endoscope) can be inserted through the cannula into the patient and then withdrawn (in the opposite direction) out from the patient and cannula.
During many such procedures, it is necessary to maintain an insufflated working space within the patient (by maintaining insufflating gas at sufficiently high pressure in the working space) while the distal end of the cannula extends into the working space. For use during these procedures, the cannula must be provide with a seal or seals for preventing undesired fluid escape from within the patient out through the cannula. The term “fluid” is used herein to denote either a gas or a liquid. One such seal will prevent fluid escape from the cannula when no instrument occupies the cannula's channel. A fluid seal is implemented in the form of a flapper valve, a duckbill valve, or other valve, which is biased in a closed position at times when no instrument occupies the cannula's channel to provide a fluid seal preventing fluid flow through the instrument at such times. When the distal end of the instrument is inserted into the channel and the instrument has advanced through the channel toward the patient, the instrument opens the fluid seal.
Typically, an additional seal is employed in a cannula to provide a fluid seal around the instrument's outer periphery and to prevent fluid flow through the space between the instrument and the wall of the channel. Such instrument seals are very important for enhancing the ease with which a medical procedure can be carried out. In many shoulder surgeries, up to twenty gallons of fluid can be used during the surgical procedure. Ultimately, the fluid must escape from the human body in one direction or another. In certain circumstances, when poor seals are used, the water is continually escaping around the periphery of the instrument onto the surgeon, the surgical assistants, the patient and the operating room environment. The rapidly escaping liquid greatly complicates the ability to carry out a simple and safe surgical procedure. In general, all prior art instrument seals have proven to be very ineffective at preventing the liquid escape through the interior of the cannula. As such, a need has developed with which to make an instrument seal which effectively prevents the loss of liquids around the periphery of the instrument during the surgical procedure.
In the past various patents have issued relating to such instrument seals. For example, U.S. Pat. No. 5,727,770, issued on Mar. 17, 1998 to W. G. Dennis, describes a double valve cannula seal for preventing the escape of liquids or gases through the cannula. The seal has a diaphragm valve with a circular aperture to seal the cannula when an instrument is inserted and a spilt conical valve to seal the cannula when no instrument is present. A pair of diametrically opposed ribs are positioned beneath the end member and are aligned with the split in the conical valve so as to abut the open end of the cannula and act as pivot points to impart compressive force against the two halves of the conical valve to improve the effectiveness of the seal.
U.S. Pat. No. 5,797,888, issued on Aug. 25, 1998 to I. Yoon, teaches a cannula with a universal seal. The cannula is an elongate tubular body having a distal end adapted to be disposed within the anatomical cavity and a proximal end adapted to be disposed externally of the anatomical cavity. A seal member is disposed along the tubular body of the cannula. A tubular pusher is disposed in the tubular body and insertable through the seal to move the seal member from a normally closed position preventing fluid flow through the cannula to an open position allowing instruments of various sizes to be introduced through the tubular body via the tubular pusher without contacting the seal.
U.S. Pat. No. 5,989,224, issued on Nov. 23, 1999 to Exline et al., discloses a universal seal for use in endoscopic surgery. A two-part seal housing encloses the universal seal in an annulus surrounding an insertion port. The outer periphery of the universal seal is clamped between the two parts at the outer edge of the annulus. An inner ring of the universal seal is free to move from side-to-side within the annulus while maintaining rubbing contact with the upper and lower surfaces of the annuluses for vertical support. The seal housing and universal seal are mounted on a proximal end of a cannula which allows access therethrough for the endoscopic surgery. U.S. Pat. No. 6,551,282, issued on Apr. 22, 2003 to Exline et al., also teaches similar type of seal for use on a cannula.
U.S. Pat. No. 6,159,182, issued on Dec. 12, 2000 to Davis et al., provides a reusable cannula with a disposable seal. The seal assembly is designed for use with the cannula during a simple medical procedure. The seal includes both a flapper valve fluid seal and at least one instrument seal. The seal assembly has a body and a flange that can be snapped onto the cannula before use and readily removed after use. The flapper valve has a over-centered hinge. The sealing flange seals the cannula when a medical instrument is inserted through the seal assembly even when the sacrificial flange has been cut during insertion of the instrument.
It is an object of the present invention to provide a seal for use in a cannula which prevents liquid escape therethrough.
It is another object of the present invention to provide a cannula seal that can be adapted to various diameters of instruments.
It is a further object of the present invention to provide a seal for use in a cannula which allows full use of the instrument even when the seal is in liquid-tight engagement therewith.
It is still a further object of the present invention to provide a seal for use on a cannula which is easy to use, relatively inexpensive, and easy to manufacture.
It is a further object of the present invention to provide a cannula having an adjustable length.
It is still another object of the present invention to provide a cannula whereby a vacuum can be connected to the cannula and whereby a common syringe can be used for introducing liquid into the inflatable seal.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.